The existing methods of measuring the temperature of a body in microwaves consist of placing a probe in the vicinity of the surface of the body, or in contact with this surface, for the purpose of picking up the signals of thermal noise emitted by a volume of the body being investigated by the probe. The thermal noise signals are then amplified, processed if necessary, in such a manner as to output a signal which is a function of the temperature which prevails in the volume under investigation.
It must be noted that in such methods the volume under investigation depends on the nature of the body and on the characteristics of the probe used. Hence, for the same body, the volume under investigation remains approximately similar to itself, especially when the probe is displaced in relation to the surface of the body.
Hence, when the purpose of a device for carrying out one of the existing methods is to detect a possible local deviation of temperature, under the surface of a body, for example, of a living tissue, it will in fact be possible to locate this anomaly when it is included in the volume which is being investigated by the probe. However, it will be difficult, even impossible, to locate this anomaly within the volume under investigation.
Hence, diagrammatically, the spatial resolution of the existing devices is limited to the volume under investigation associated with the probe. In order to improve this spatial resolution, it is now possible to change the probe, in such a manner as to change likewise the volume associated with it. However, such a change requires manipulations and adjustments for adapting the chain of measurements to the new probe.
On the other hand, it must be noted that for a volume under investigation associated with a probe, the signals emitted by elementary volumes closest to the probe present, at the level of the latter, a greater weight than the signals emitted by elementary volumes which are further away. In other words, the signals emitted by elementary volumes close to the surface of the body mask those emitted by the rest of the volume under investigation.